Previous research on the tumor-dormant state that is established in DBA/2 mice with syngeneic L5178Y lymphoma cells has consisted principally of identification of host responses to L5178Y cells and of characterization of L5178Y clones isolated from the peritoneal cavity at three key stages of the tumor-dormant state: establishment, maintenance and eventual termination and formation of an ascitic tumor. In this research, we will subject tumor-dormant mice to various perturbations of those host responses and of the tumor cell population. As a consequence, the tumor-dormant state may be prematurely terminated with either cure or formation of an ascitic tumor, or may be prolonged. The mechanisms involved in termination or prolongation of the tumor-dormant state by any of these perturbations will be determined. We will evaluate peritoneal host cell function, soluble factors in the peritoneal cavity and the tumor cell phenotypes. Tumor-dormant mice will be mated and also subjected to stress to determine whether the resultant changes in the physiological state of the mice affect the tumor-dormant state.